horse; block of rock separated from surrounding rock
Geological term for a block of rock completely detached from the surrounding rock by mineral veins or fault planes. The gloss 'horse' is a direct translation of the Japanese term 中石, but the explanatory gloss is clearer for learners.
In this mine, horses are frequently found.
A horse completely separated from the surrounding rock by a fault was observed.
The term 中石 (なかいし) literally means 'inside stone' or 'middle stone', likely referring to a rock body enclosed within a different rock mass. The English equivalent 'horse' is a mining term of uncertain origin, possibly from the idea of a 'horse' being a large, obstructive block.